1. Field of the Invention
The present invention relates to rotary brushing implements.
2. Description of the Prior Art
Numerous types of apparatus employ rotary sweeping or brushing implements. Typical of such apparatus are street cleaners in which the rotating brushing implement is used to pick up trash off the street and place it on a conveyor or in a bin for disposal. In the street cleaner field, implements are often called "brooms" and the term is so used herein.
In a typical rotary broom in use today, the bristle portion is initially formed as a strip having a channel in which the bristles are seated and which is crimped to retain the bristles. The bristle portion is then placed on a core or mandrel to form the rotary broom.
Numerous kinds of brooms are currently available. In one such broom, the strip is helically wound around the mandrel and permanently affixed to the mandrel. The broom is sold as a prefabricated, disposable unit. This approach features easy, rapid replacement in the street cleaner but with shipping bulk and loss of the mandrel at each refill.
In another variation, the strip is severed and formed into doughnut-like wafers which are slid on the core between spacers. This approach permits reuse of the core and some reduction in shipping bulk but at higher installation cost.
In a further variation, a groove or track is provided along the exterior of the core into which a helical strip of bristles is threaded. Shipping bulk is minimized since the volume of the collapsed helix is small. But replacement of the strip becomes difficult as the track on the core becomes clogged with dirt and rust.
A recent development in rotary brooms utilizes a so-called "trackless core" in which the track or groove is omitted. See U.S. Pat. No. 3,750,225 to Gould. The ends of the strip are affixed to the ends of the core and the intermediate turns of the helical broom are free to move or "float" with respect to the core. Such a broom is small in shipping bulk and economical in replacement.
However, in use, the rotation of the broom on the street produces circumferential movement of the strip intermediate the ends of the strip. Existing designs have sought to remove the slack produced by this movement to avoid reducing the sweeping efficiency of the broom through imbalance and to prevent damage or eventual destruction of the broom. Slack removal also holds the strip tightly on the core during all operative states of the broom. U.S. Pat. No. 3,750,225 shows an automatic slack accumulator which takes up the slack at one end of the strip. However, an automatic slack accumulator may fail to work adequately in the service environment. U.S. Pat. No. 3,193,866 to Jones shows a tracked core broom with a non-automatic slack remover. The operation of the broom must be periodically stopped to remove the slack. This tends to be inefficient and impractical.